1. Field of the Invention
The present invention relates generally to medical apparatus; more particularly, to operating controls for such apparatus; and, even more particularly, to foot-operated controls for medical apparatus and the like.
2. Background Discussion
Most powered medical apparatus include operating controls for setting and/or regulating parameters or functions of the apparatus. Such medical apparatus which require only an initial set up or only minor control adjustments during operation, usually locate all the controls in or on the apparatus cabinet, as opposed to remotely locating the controls, as is discussed below. Typical of such medical apparatus are simple X-ray machines, for which the operating parameters are usually preset by cabinet mounted controls before an X-ray is taken.
Numerous types of medical apparatus include, as part of the apparatus, a connected, hand-held medical implement or tool, some operating parameters or functions of which must usually be controlled during use. A familiar example of such medical apparatus are dentists' drilling apparatus which typically include a power source having connected thereto a hand-held drilling implement which requires drilling speed regulation and on/off control during its use on dental patients.
Another, perhaps less familiar, example of such medical apparatus are phacoemulsifier apparatus which are especially constructed for surgically removing the natural, crystalline lenses from cataract eyes in preparation for the insertion of an artificial intraocular lens. Phacoemulsifier apparatus typically comprise a cabinet, which contains a power supply, vacuum pump, electronic, and associated hardware, and a connected multi-function, hand-held surgical implement having a slender hollow needle-like tube which is inserted into a patients eye in order to perform the phacoemulsion operation. Functions of the phacoemulsifier hand-held surgical implement include irrigating the eye (with a saline solution), ultrasonically emulsifying (disintegrating) the eye lens, aspirating (by vacuum) the emulsified lens, cauterizing broken blood vessels, and vitrectomy (removing vitreous humor from the eye). It can be appreciated that a surgeon using the hand-held implement to perform such functions requires the ability to control these functions, as well as the ability to selectively shift or switch between at least some of the functions (for example, irrigation and irrigation plus aspiration) as the need arises during phacoemulsion surgery.
It can be appreciated that for such medical apparatus as dental drills and phacoemulsifiers, which require the use of hand-held implements for operations during which the operator requires functions of the implement to be shifted and/or varied, the complete controlling and/or shifting of functions from remote, cabinet-mounted controls is generally unsatisfactory. Normally, the person using the hand-held implement is too involved in the medical procedure to be able to operate remotely located, cabinet-mounted controls. On the other hand, having an attendant operate the cabinet-mounted controls is even less practical except, perhaps, for simple medical procedures and apparatus.
Such problems associated with adjusting cabinet-mounted controls while operating an associated hand-held medical implement may be overcome, in some simple cases, by mounting controls directly on the hand-held implement. This may, for example, be satisfactory when the only control required is to turn a function performed by the hand-held implement on and off and/or to vary an operational speed of a function performed by the implement. Then, the including on the implement of a ON/OFF microswitch perhaps with the additional inclusion of speed control, may be feasible for some medical apparatus (the implement then being analogous to a conventional, hand-held, variable-speed electric drill used by caprenters and homeowners). However, surgery performed by a skilled surgeon requires extremely precise control and, therefore, attempting to control a function with the same hand that is simultaneously manipulating the hand-held implement to perform a delicate operation is generally not preferred.
As an alternative (or a supplement) to cabinet-mounted and/or hand-held implement-mounted controls foot controls are frequently provided for medical (and other) apparatus, thereby freeing an operator's hands so that he or she can concentrate on manipulating the hand-held implement. Some such foot pedal controls, for example, have heretofore used one or more electrical switches mounted along the path of pedal movement so as to enable one or more operational functions to be respectively turned on and off by the operator depressing and releasing the foot pedal. In addition or alternatively, electric potentiometers have heretofore been connected to the pedal to enable the varying of an operational function by analog means according to the angle through which the pedal is displaced by the operator.
Mechanical detents are also known to have been used for providing increased resistance to angular pedal movement at preestablished detent points, thereby providing a sensory warning to the operator that slightly further pedal depressing will cause a given event to occur. For example, such detents may be used to alert the operator to the turning off of one operational function and the turning on of another function by a control switch or switches mounted in the path of pivotal pedal movement.
Heretofore, however, foot pedal controls for medical apparatus and the like have, so far as is known to the present inventor, been analog (as opposed to digital) types and have had, at least partly as a result, a number of deficiencies and disadvantages, some of which are serious. One disadvantage is that known analog foot pedal controls cannot be electronically "reprogrammed" to control different functions or combinations of functions, as is often important for use with multi-function apparatus, such as the above-described phacoemulsifiers. Another disadvantage is that when mechanical detents are used on analog foot pedal controls to alert the operator to an impending event, such as a switch being actuated, the detents tend to become worn with use and may eventually fail to provide sufficient additional resistance to pedal movement to give the desired warning to the operator. On the other hand, mechanical detents may become dirty and tend to stick, and may, therefore, result in excessive pedal pressure having to be applied to overcome the detent, thereby possibly resulting in greater-than-intended pedal travel and failure of proper foot pedal control once the pedal is moved past the detent position.
For these and other reasons, improvements in foot pedal control systems, particularly for use with medical apparatus, are needed; and it is a principal objective of the present invention to provide such an improved digital foot pedal control system which is particularly suited for controlling multi-function apparatus.